Method for the production of metallic printing plates or cylinders



PM Nov. 21, 1939 z,1s1,'111 Ils'mon ron. m rno'nucnon or rammam'ms on.

Two

Josef Horn, Dresden,

m. invention rum; to a method duction of metallic printing plates or cylinders comprising a plurality of layers, for book print- There are already known printing plates or blocks comprising severalmetallic layers, example, for book printing, e. g., zinc blocks or m copper plates or cylinders for intaglio printing.

In order to increase theresistance to wear of such known printing plates, after the picture to be minted was applied thereto and finally cast or etched, such plates were nickel-plated or 15 chromium-plated.

In the case of printing works or chemigraphical works which do not have their own metal electrodepodting plants, the cast or etched printing plates are first brought toso-called galvanoplastic 2 installations, in order that the prinflnl plates or cylinders may there be nickel-plated, chrom iumplated or coated with zinc. absorbing and expensive. operation for printing works. Further, etched printing plates or cylinders which are subsequently provided with a metallic coating suffer from the drawback that with fine mesh autotypes the dots contract in consesubsequently applied metallic deposits and aii'ect unfavourably the truth to tone so of the picture.

4 There are also tallic printing ample, a metallic layer is applied by. metal already known multi-layer meatomisation or metal spraying to a base of copper 35 (E nickel.

The metallic l yers produced by'metal sprayon nickel or copper platesserve only to provide on such plates a porous grain adapted for retainingmoisture. but not for etching high or m deep a picture applied to the layer formed by metal atomisation.

If a picture is applied to one of the, known Bases consisting of iron, steel or other hard subsequently'applied metallic plates or blocks in which, for exflexibility of the experience, a. picture with the PATENT OFFICE 1n:- crunnns Gcrmannllllgllord percenttoErlchWebcr;

NoDrawing. Application May 88,045. In German Dresden,

:1. 1m, Serial no. May :9. ms

3 Galina. 4141.5) for the pro-' recent rotary printing machines; Further, iron and steel printing plates or blocks which come from the rolling mill have not such a uniform continuous smooth and close surface as is' necessary for printing plates, even if the iron or steel bases are ground or polished before application of the metallic coatings.- The treatment would also so increase the cost of the bases that they could not be economically used in the printing industry. In another known printing plate the base also consists of steel which is plated with silver, nickel or. copper. It is evident that these coatings do not-serve to render the picture carrier more durabases suifer from the drawback of being diilicult to bend and work on. Reference may also be made to a known metallic printing plate (mercury) with several metallic layers for pianographic printing, where'the upper layer applied to an iron basis consists of nickel which is'etched through at the non-printing areas down to a copper layer which is then caused-to form an amalgam. Apart from the fact that mercury printing plates have not been approved in prac- I Qtice, because they constitute a danger to health, and because the amalgamated copper faces repel the ink in a very defective manner, such printing plates have nothing in common with the subject of the application as they are planographic printing plates, while the subject of the application is concerned with printing plates having the inked areas in relief. The mercury printing plates are referred to only for the purpm of explaining the state of the art.

According to the invention the above mentioned drawbacks are avoided, and in metallic printing plates or blocks for book printing and for relief platen printing there is obtained a very durable picture carrier, true to tone value, with easy printing plate. In relief printing plates according to the invention, besides wear-resistant picture carriers of correct tone value and with the maximum ease of flexibility of the plate, there is obtained my and satisfactory repulsion of the ink at the non-printing areas. This result is realised in that on a-base of zinc, .cadmium, tin, suitable light metals such as aluminium, magnesium or alloys thereof, for example, on zinc or aluminium plates, depending on the printing work to be eiiected. there is or are firmly superimposed one or more layers of copper, brass, tombac, tin, lead, aluminium, nickel, iron, 5

steel, manganese, chromium, alpaca, silver or alloys thereof, for example electrolytically or chemically, before the picture to be printed is transferred to the metallic layer which carries the picture, and the non-printing areas are deepened, etched, engraved or shaved. In this case the up per metallic layer or layers may be etched through, engraved or shaved at the non-printing areas. With relief printing plates this is desirable because then the underlying base, for example, one of zinc, can be readily made ink-repellant in manner known per se with 'a thin etch and water or aqueous solution.

A further very good example of such easily bendable relief printing plate with a picture carrier of great resistance to wear and'correctness of tone value consists in a base plate of aluminium which is provided with one or more thin coating layers of copper or copper alloy. The picture is transferredin manner known per se to the upper cuprous carrier which is then etched away at the non-printing areas with dilute nitric acid, so that at these areas the aluminium or aluminium alloy or a thin metallic intermediate layer thereabove is caused wholly oralmost wholly to appear. With suitable previous treatment these areas do not take up ink, but only the metallic layer of durable, copper-containing picture-carrier in relief is inked. As dilute nitric acid attacks only the copper alloy, but notoriously does not attack aluminium, it is impossible: to efiect. too. deep etching of the vacant points.

The correctness of tone value of the original, for example, of the negative, which is copied on the upper copper-containing layer is thus maintained in the cuprous picture carrier etched in relief.

In these examples the printing plates thus comprise bases of the easily flexed metals, zinc or aluminium, and the upper metallic coating or picture-carryinglayer consists of hard wear-resistant metal, for example, copper or copper alloy. By etching away the upper metallic layer at the vacant points there is obtained a relieved cuprous picture, correct to tone, on an easily flexed and readily worked base plate. Between the base plate of zinc or aluminium and the upcopper or copper alloy there may naturally also be interposed the other metallic layers or some of the previously mentioned metallic layers.-

Printing plates produced by the method just described present also the advantage that now also the offset printercan print with durable metallic original etchings .of the correct tone value, which previously only the book printer was able to do.

To print with metallic wear-resistant original etched reliefprinting plates in order to produce offset printing similar to that of book printing has been for a long time the desire and aim of the ofiset printer. By the invention account is taken therefore of along felt want.

' A similar good example is realised if there is applied-to a light metal base, for example an aluminium plate by fusion a thin iron layer which is deeply etched at the points free from the picture. Also in this case there is obtained a very durable relief picture carrier.- This example can be used both for book-printing as also for onset relief printing.

Reference is still made. to a further desirable example of a printing plate consisting of multiple layers of metal for'book printing or for relief printing. In this case the base consists of suitse to this brass layer,

magnesium or electrolytically and they should not be cadmium, and thereon there is superimposed a layer of copper alloy, for example, brass. The picture is then transferred in manner known per which is deeply etched at the points free from the picture or is etched through down to the zinc or cadmium layer or down to the light metal base. The intermediate layer of zinc or cadmium ensures perfect adhesion of the brass layer to the light metal base.

Further, the said intermediate layers ensure uniform smooth continuous closeness of the 'brass layer. For fine mesh autotypes for ofiset printing this is a great advantage.

There may also be obtained a good example if to a base of zinc or other suitable light metal base there is applied a layer of tin, lead or amalgam and there is superposed on said layer a layer of copper alloy, for examplea brass layer, and the points free from the picture are completely or almost completely etched away. The iron or tin or lead or amalgam layer enters into such a close combination with the light metal base which is exposed substantially throughout the non-printing areas and which in offset printing repels the ink very well at these areas.

It may also be mentioned that if on a base of zinc, cadmium, aluminium, tin or alloys thereof several metal layers are superimposed, such layers may consist ofdifierent metals; for example, on a zinc base there may first be superimposed a copper layer and then a'silver layer. The transfer of the picture to the picture carrier may be effected by copying, etc.

Instead of elemental metal layers also metal oxide layers may be electrolytically formed on a suitable light metal base such as aluminium or alloys thereof, and then the picture maybe applied to such metal oxide layers and made ready for printing in the manner already described.

An important advantage is realised if the base of light metal is somewhat roughened or grained then the other metal layers are applied thereto. If the covering metal layer or layers is etched away at the points free from the picture down to the electrolytically grained light metallic base there is realised perfect retention of moisture, which is advantageous for offset printing.

Printing plates according to the invention may be provided not only on the front side but also on the rear side with the aforesaid metal covering layers, whereby an economic advantage is realised by saving of material, because both sides of such printing plates can be used.

In view of the fact that many of the metallic layers mentioned in the foregoing description must be etched with somewhat stronger acid solutions than migraphy for zinc, it is recommended not to treat with bichromated gelatin or albumen the lightsensitive layer which lies on the upper metallic layer and on which the picture is copied, but to use a so-called copying lacquer which is developed by means of alcohol. The subsequent removal of the copying lacquer may be assisted by solvents, for example, spirit.

In order to eii'ect better adhesion to one another of the metallic layers it is important that polished before another layer is' superimposed thereon. Also the uppermost are commonly necessary in che-,

printing, drawin large area are -d1rect printing and 80 printing.

metallic layer need not be polished and around before the light-sensitive layer or the Picture is applied to the upper metallic layer. 1

The said metallic covering layers may not only be produced electrolytically or chemically but also by a metal spraying process or by hot rolling 'of copper on aluminium or by other methods.

As in offset printing works mainly 1:300:10! used, the electrolytic ap ca on of the metal layers with the n orm thickness presents certain dimculties with large iormes, in respect that the layer deposited onthe printing plate is finer in the middle than at the 4 which render it possible to obtain a uniform layer.

Further, it is recommended in the galvanic application 01' the layer or layers of copper, brass, tombac, tin, lead, aluminium, nickel, .chromi alpaca, or silver on a base of zinc, cadmium. aluminium,- tin or alloys thereof to use alkali fine mesh drawings.

It may be mentioned also that printing plates according to theinvention may be used both for cadmium. and alloysalso ior indirect or oilset 3 I claim: i. The method of producing metallic printin plates or cylinders for relief printing, which 3 upon a pliant ground plate of light metal selected from the group con- 5 sisting of aluminium, magnesium and alloys thereof, at least one intermediate layer of a met al selected from the group consisting of zinc, thereof, superimposing on said intermediate layer or layers at least one layer oi heavy wear-resistant metal characterized is grained by electro-chemical treatment prior the superimposition of the intermediate layer. 8. me method of producing metallic printing plates or cylinders for relief printing as set iorth in claim 1 in which the hard wear-resistant sur- .face layer is deposited on the intermediate layer electrolytically from an alkali cyanide bath.

Josm norm. so 

